WO2000051862A1 - Method for controlling a vehicle - Google Patents

Abstract

The invention relates to a method for controlling a vehicle, especially the traction control system (ASR). A diagonal axle twist is detected and evaluated as a regulating variable.

Description

Vehicle control procedure

The invention relates to a method for vehicle control, in particular a traction control system, as well as a method and a circuit arrangement for recognizing a diagonal axis interlocking of a vehicle with all-wheel drive.

Vehicle controls are known which reduce the wheel slip to a value necessary to ensure traction and driving stability by the build-up of brake pressure on overturning drive wheels and give the standing wheels a stronger drive torque. These exist for both two-wheel drive and four-wheel drive vehicles. These vehicle regulations are referred to as traction control systems (ASR). The terms "electronic differential lock (EDS)", automatic stability control (ASC) "or" traction control system (TCS) "are also used for these regulations.

There are two types of ASR systems: ASR and brake ASR (BASR) or brake TCS (BTCS). In certain situations, ASR also throttles the engine torque in order to keep the load on the brakes as low as possible. Brake ASR only works via automatic brake intervention. In the following, the term “ASR” means all conceivable traction control systems, that is to say those with and without intervention in the engine management.

The design of the traction slip aggregate systems is basically carried out for use on the road characterized by largely flat ground and at least approximately the same coefficient of friction on some sides. If an all-wheel drive vehicle without a differential lock drives off-road over a diagonal furrow, so that contact with the ground is lost on a diagonally opposite front wheel and rear wheel, these two wheels spin and thus prevent drive torque from being applied to the two wheels on the wheel (the two along the other Diagonally opposite wheels) is given. Since the vehicle tenses up considerably, this situation should be overcome as quickly as possible. This requires vigorous propulsion to move the vehicle. An ascending road surface or an abrupt obstacle, for example a stone, in front of one or more wheels further complicates the situation.

In this case, sufficient traction can only be achieved with the help of a differential lock. In practice, it can be seen that the measures implemented in the previous ASR systems are not sufficient, since excessive slip values are usually tolerated on the spinning wheels. The brake pressure is held in the brakes for too short a period of time on the relieved wheels, so that a locking effect comparable to a differential lock does not occur.

The driven wheels of a vehicle diagonal alternately get into the drive slip and the engine torque oscillates between the wheels in question depending on the current wheel load, the brake pressure and the engine torque. The pressure modulation in the driven wheels lags behind the drive slip. A steady state does not appear. The vehicle gets stuck.

The problem will be clarified with the help of the following consideration. The power PB consumed in a wheel rotating at constant speed U / t and subjected to constant braking force FB is:

PB = FB * vB = FB * 2 * _π * r _eff * u / t (1)

Here r _{eff is} the effective wheel radius at which the braking force acts. U / t should be given in the unit wheel revolutions per second.

Assuming the example that the left front wheel and the right rear wheel are spinning on a diagonal furrow and are braked by the traction control, the following equations result for the power consumed:

PB1 = FBI * vBl = FBI * 2 * π * r _effl * Ul / t (2.1)

PB3 = FB3 * vB3 = FB3 * 2 * π * r _eff3 * U3 / t (2.2)

The wheel indices are selected clockwise:

1 = left front wheel

2 = right front wheel

3 = right rear wheel 4 = left rear wheel

Assuming that the brakes on the wheels are roughly the same dimensions and the speeds of the spinning wheels and the braking forces are also the same, the total power can be stated in a simplified manner:

PBges = FB * 4 * π * r _eff * U / t (3)

The total braking torque MBges applied by the wheels, which via the axle differentials or the center differential al acts on the other wheels as total drive torque MAges, is:

MAgeS (spinning wheels) ⁼ MAg ^β S (traction wheels) = FB * 2 r _e ff (4)

It can be seen in equation (3) that one can easily consume the entire engine power with a sufficiently high speed U / t of the spinning wheels and an average braking force FB. If the braking forces FB are too small, only a small drive torque is provided in accordance with equation (4). In extreme off-road situations, especially with diagonal entanglement, a high peak torque is required, at least for a short time, to free the vehicle from the "jamming situation".

This situation occurs relatively frequently on uneven floors, since a strong unevenness always leads to the lifting of one wheel and to the tilting over a diagonal that does not include the lifting wheel. The wheel that is diagonal to the lifting wheel will also lose its contact force in most cases in whole or in part, depending on the direction of tilt and the inclination of the vehicle.

The object of the invention is therefore to improve a method for vehicle control, in particular for driving situations on uneven floors. According to a subtask, a method and a circuit arrangement are also to be provided with which a diagonal axis interlock, which was caused in particular by a driving situation on uneven floors with diagonal furrows or abrupt obstacles, is reliably recognized.

The object is achieved according to the invention by a method for vehicle control, in particular for traction control (ASR), which is characterized in that a diagonal axis interlock is determined and evaluated as a controlled variable.

In the method for vehicle control according to the invention, the situation of a diagonal axis interlock is first determined. The state of the axle interlock is then evaluated as a controlled variable for vehicle control. According to this controlled variable, a targeted intervention, in particular of the vehicle control system, can take place, for example, in brake control, engine management, the transmission function and / or the function of differential locks.

According to the invention, the effect of partial or complete locking of a center, front axle and / or rear axle differential is achieved after determining the diagonal axle interlock, using means of the vehicle control system, in particular dimensioning and / or modulating the brake pressure in the wheel brakes of the controlled wheels and / or a center, front axle and / or rear axle differential is partially or completely locked with the help of an optional differential lock.

The method _ initially includes the detection of the need for a cross-locked state and the subsequent setting of the cross-locked state using means of the vehicle control system, preferably with brake control by the traction control system, with one or more differential locks which may be present, for example a center differential lock can be switched on. However, it is also possible to use one or more differential locks, if any, as an alternative to brake control. It is further provided according to the invention, in addition to the brake intervention, an intervention in the To perform engine management, for example by controlling actuators such as throttle or ignition.

It is provided according to the invention that, after the diagonal axle lock has been determined, an average brake pressure level on the wheel brakes of the regulated wheels corresponding to the required traction is set with a minimum drive slip and maintained for a certain period of time.

Sufficient traction is achieved in this case by holding the brake pressure on the relieved wheels in order to produce a locking effect comparable to a differential lock in the brakes for a period of time until the situation of the diagonal axle lock is overcome. The periodic oscillation of the engine torque between the wheels of a vehicle diagonal as described at the outset is thus carried out after the axis interlocking has been recognized by the method according to the invention

Elimination of lagging of the brake pressure safely prevented. The locked state of the differentials or the comparable effect of a locked state is advantageously retained for a period of time which is chosen so that it is sufficient to move the vehicle over the obstacle. The speed U / t of the spinning wheels is reduced by braking more heavily. This also results in a clear comfort advantage, wheel scratching is largely avoided and the engine speed remains relatively low at all times. In addition, tire wear is minimized.

The regulation of the affected wheels takes place according to the invention at relatively small slip values, preferably less than 30 km / h, so that increased pressure levels occur at the wheel brakes. In extreme cases, the wheels are braked down to traction slip values close to zero (0).

An increased pressure build-up and a delayed pressure reduction in the brake pressure can advantageously be achieved by changing the pressure build-up and reduction gradients. The pressure modulation can be changed further by a faster pressure build-up or a slow pressure reduction. This can be achieved by shortening the pause time during the pressure build-up and lengthening the pause times during the pressure reduction with unchanged pressure build-up or pressure reduction pulses or by increasing the pressure build-up pulses and reducing the pressure reduction pulses with unchanged pause times.

According to the invention, the control threshold of the traction control system is additionally lowered after the detection of a diagonal axis interlock.

Lowering the ASR control thresholds further reduces drive slip. This manipulation of the control threshold in the case of a recognized terrain situation of a diagonal axle interlocking advantageously takes place only on the wheels in an active ASR control. It is then advantageous to control only the wheels concerned with small thresholds in order to avoid stable wheels from entering an ASR control phase.

According to a further embodiment of the invention, it is provided that the determined diagonal axis interlock is evaluated as a controlled variable and / or a corresponding control function of the vehicle control is only activated when the vehicle speed, in particular a calculated or estimated vehicle reference speed, is one predetermined vehicle speed limit, preferably in the range from 3 to 15 km / h, special approx. 6 km / h, falls below. Since the situation of a diagonal axle interlock basically represents a standard situation on uneven surfaces and thus especially in the terrain, a partial or complete locking of a center, front axle and / or rear axle differential takes place and / or such an effect is achieved with the aid of the traction control system with the help of these Procedure only carried out if there is a correspondingly low vehicle speed.

According to the invention, a diagonal axle lock of a vehicle with all-wheel drive and vehicle control, in particular traction control (ASR), is recognized with a method which is characterized in that the diagonal axle lock is based on the wheel slip, the turning behavior and / or changes in turning behavior of the individual driven wheels is determined.

For the purposes of the invention, the term “vehicles with all-wheel drive” encompasses both vehicles with permanently at least four driven wheels on at least two driven axles, and primarily vehicles driven with one axle, in which a second axle can also be activated if necessary. This can be done manually or automatically, for example using a viscous coupling.

This method advantageously recognizes the situations in which an all-wheel drive vehicle drives off-road over a diagonal furrow. By determining the

Rotational behavior or changes in rotational behavior can be detected in particular if the ground contact is lost on a diagonally opposite front wheel and rear wheel and these two wheels spin. According to a preferred embodiment of the invention, the rotational behavior of the individual driven wheels is measured and evaluated to determine the drive slip and other control variables, and a diagonal axis offset is determined on the basis of a drive slip of the individual wheels which is above a predetermined limit value.

According to the invention, it is provided that a diagonal axis offset is determined on the basis of the rotational behavior of rotational behavior and / or of rotational behavior changes of at least two transversely opposite wheels and of two diagonally opposite wheel pairs.

For the purposes of the invention, the term “transversely opposite wheels” means that the two wheels are located transversely with respect to the longitudinal axis of the vehicle. It is therefore a right wheel and a left wheel of a wheel axle. Overlying wheel pairs "here are the two wheels opposite each other along a vehicle diagonal, that means the right front wheel and left rear wheel (first vehicle diagonal) as well as the left front wheel and the right rear wheel (second vehicle diagonal).

It is provided in accordance with the invention that a diagonal axis interlock is determined when certain traction slip conditions are met for a predetermined period of time.

According to the invention, a diagonal axis interlock is determined when the following conditions are met for a predetermined period of time, that a) there is traction slip on a wheel on the secondary axis that is above a predetermined limit value, b) on both of two diagonally opposite one another Wheels of a wheel pair res there is a drive slip that is above the predetermined limit value and c) there is a drive slip that is below the predetermined limit value on a first wheel of the primary axis, which first wheel is opposite a second wheel of the primary axis with a drive slip that is above the predetermined limit value or at least a lesser one Brake pressure, in comparison to the second wheel of the primary axis with a drive slip that is above the predetermined limit value, is present in the wheel brake of the first wheel of the primary axis, which first wheel is opposite the second wheel of the primary axis with a drive slip that is above the predetermined limit value.

The term "primary axle" here means the axle which is driven first by the motor or generally the axle with a higher driving torque or greater contact forces. The primary axle is further characterized in that the wheels of the primary axle are compared under the assumption of the same driving conditions first come into a drive slip to the wheels of the secondary axle. The term "secondary axle" is used here for the axle via which no or only a lower drive torque is transmitted in the state without a drive slip. Only at a corresponding differential speed is a larger drive torque transmitted on this secondary axis in accordance with the traction control system.

According to the invention, the state of a diagonal axis displacement is determined when conditions a) to c) are met for a period of 0.3 to 1.5 seconds. The exact value can be determined individually by relatively few tests. It depends on the dynamics of the drive train of the respective vehicle. In one case, for example, a value of approximately 0.7 seconds has proven to be particularly favorable. According to the invention, a diagonal axle lock is determined when the particular traction slip conditions are fulfilled for a relatively short period of time, preferably 50 to 200 msec, in particular approximately 100 msec, and when the diagonal axle lock determined last is at most a few seconds, preferably 5 up to 15 sec, in particular about 10 sec. Here, the diagonal axis interlock is already recognized if the pattern or the conditions of the traction slip is present in a relatively short period of time, for example approx. 100 msec, and if the situation of the diagonal axis interlock beforehand, within a follow-up time of approx. 10 seconds, for example has already been determined.

It is provided according to the invention that a traction slip, based on the wheel rotation speed of the spinning wheel, of the order of magnitude between 10 km / h to 40 km / h, preferably approx. 30 km / h, is specified as the traction slip limit value.

According to a further embodiment of the invention, it is also provided that the traction limit value on a wheel is considered to have been exceeded when a control process of the traction control system starts or stops on the respective wheel. The traction control system is active when it regulates pressure build-up, pressure maintenance or pressure reduction on the respective wheel brake.

In the method for vehicle control, in particular for traction control (ASR), according to the invention the diagonal axis interlock is determined with the aid of a method according to one of claims 6 to 13. This ensures a reliable determination of the diagonal axis interlock. The underlying subtask is also solved by a circuit arrangement for detecting a diagonal axle lock of a vehicle with all-wheel drive and a traction control system, which vehicle has a detection circuit, for detecting measured changes in the rotational behavior of the driven wheels, which circuit arrangement is characterized in that the circuit arrangement has a first determination circuit for determining a diagonal axis offset of the vehicle on the basis of the rotational behavior changes of the driven wheels detected by the detection circuit.

According to an embodiment of the invention, the circuit arrangement is characterized in that the first determination circuit is a first evaluation circuit for

Evaluation of a slip of the wheels on the secondary axle has that the first determination circuit has a second and a third evaluation circuit, for evaluation of a slip of the wheels of the two diagonally opposite wheel pairs that the first determination circuit has a fourth evaluation circuit for evaluating one Slip of the wheels on the primary axis, and that the first determination circuit has an integrator and a signal generator, for generating a signal, if determined with the aid of the evaluation by the first, second, third and fourth evaluation circuit over a predetermined period, for a diagonal axis interlock typical slip conditions are recognized.

It is provided according to the invention that the first determination circuit is assigned a second determination circuit for determining a vehicle reference speed on the basis of measured values, and that the first determination circuit has a comparator in order to compare the determined vehicle reference speed with a predetermined limit value, and the first success averaging circuit generates a signal for the presence of a diagonal axis interlock only when the determined vehicle reference speed falls below the predetermined value.

The invention will be explained in more detail below using two flow diagrams (FIGS. 1 and 2) and a block diagram (FIG. 3).

1 shows a flowchart of an embodiment of the method according to the invention for detecting slip conditions of a diagonal axle lock in a vehicle with a primary front wheel drive in an ASR control cycle.

FIG. 2 shows a flowchart of an embodiment of the method according to the invention for determining a diagonal axis twist after the slip conditions of a diagonal axis twist, in particular according to the sequence shown in FIG. 1, have been recorded.

FIG. 3 shows a block diagram of an embodiment of the circuit arrangement according to the invention for detecting a diagonal axis interlock.

In FIG. 1, after the start (step 8), a low vehicle speed or vehicle reference speed (V _ref ) below a speed threshold (VS) is required as a basic condition for the detection of a slipping condition of a diagonal axis interlock with query 9. Since the two standing wheels do not normally overturn in the case of a diagonal axle interlock, an estimated vehicle _{reference speed} (V _ref ) agrees very well with the actual vehicle speed. In order not to unlearn the pattern when starting off, a V _ref is preferably _reduced 3 to 15 km / h, e.g. less than approx. 6 km / h, required. In contrast to the present specific exemplary embodiment (constant value), this speed threshold VS can also be a function of the detection reliability. Because with a relatively high pressure level and a relatively strong intervention of the ASR control, the vehicle speed will generally also be relatively low, as a result of which the above condition is met.

Furthermore, the ASR may only be active on one of the two wheels of the secondary drive axle, which means on wheels 3 and 4 according to the definition introduced at the beginning (Radi = left front, wheel 2 = right front, wheel 3 = right rear, wheel 4 = left rear ), which will be retained in the following. This requirement is checked when the criterion of a low vehicle reference speed (step 10) is met in step 11 with the query “ASR not active on wheel 3 or ASR not active on wheel 4”.

If condition 11 is met, the query proceeds to step 12, where the condition 'ASR on radio active and ASR on wheel 3 active' (case A) is checked. If the ASR on radio and wheel 3 is not active, the corresponding condition 'ASR on wheel 2 active and ASR on wheel 4 active' (case B) is checked in a subsequent step 13. Queries 12 and 13 detect the occurrence of slippage of the diagonally opposite wheel pairs Radi and Rad3 in case A and Rad2 and Rad4 in case B.

From the wheels of the primary drive axle (Radi and Rad2), an ASR intervention should only be carried out on the wheel located diagonally to the regulated wheel of the secondary axle. Therefore, the conditions in step 14 in case A - corresponding to an ASR-controlled radio - 'ASR on wheel 2 not active' and in step 15 - corresponding to an ASR-controlled wheel 2 - in accordance with case B 'ASR on wheel 1 not active' checked. These requirements cannot always be met in certain situations, for example if a relatively well-positioned wheel is only "torn off" for a short time, since ASR control can take place here for a short time. For this reason, the wheel that controls the mainly controlled wheel (wheel 1 in case A and bike 2 in case B) (bike 2 in case A and bike 1 in case B) at least a smaller model pressure is required. The pressure designated here as "model pressure" means a pressure calculated for a specific wheel brake.

If the conditions of steps 9, 11, 12 and 14 in case A and 9, 11, 13 and 15 in case B are met, slip conditions of a diagonal axis interleaving exist. These are recorded in step 16, otherwise not recorded (step 17).

The above-mentioned slip conditions or ASR control conditions for a diagonal axle lock of a vehicle with primary front-wheel drive can be recognized, for example, with the following query:

If ((V _r ef <VS) and a wheel of the secondary axis are not active and ((ASR active on Radi and ASR active on Rad3 and ((model pressure Radi> = model pressure Rad2) or ASR not active on Rad2)) or (( ASR active on Radi and ASR active on Rad3 and ((model pressure Radi> = model pressure Rad2) or ASR not active on Rad2 The situation is similar for primary rear-wheel drive, whereby the pressure conditions and the 'ASR not active' condition apply accordingly to the wheels of the rear axle (wheels 3 and 4).

Following the detection of the slip conditions of a diagonal axis interlock in an ASR control cycle shown in FIG. 1 (step 16), the state of a diagonal axis interlock is advantageously determined in accordance with the flow chart shown in FIG. 2 (step 19). If the slip conditions for a diagonal axis interlock are recorded in an ASR control cycle (step 20), a first counter (COUNTER 1) is carried along, provided that the value of the first counter is below a certain maximum value (COUNTER 1 _max ) (step 21) in the subsequent step 22 incremented by 1.

Otherwise, if the slip conditions in step 20 are not met and if the first counter has a value greater than zero (0) (step 23), the first counter is decremented by 1 in the subsequent step 24, the decrease down to the value zero (0) is performed.

For example, these conditions can be identified with the following query:

If (above condition met) {

If (COUNTER1 <COUNTERl _ma χ) COUNTER1 = COUNTER1 + 1

}

On the other hand (if the above condition is not met) {

If (COUNTER1> 0) COUNTER1 = COUNTER1 - 1 Subsequent to step 22 is then checked in step 25 whether the value of the first counter exceeds a threshold value (ZÄHLERlii _m i), which threshold value is below the maximum value _max Counter List. If the first counter is greater than the threshold value COUNTER _{in the} , this means that the conditions mentioned were recognized in succession over a certain period of time, for example 0.3 to 1.5 seconds, preferably about 0.7 seconds. It is then assumed that the situation of a diagonal axis interlock has been recognized (step 26). A signal for the presence of a diagonal axis interlock can then be generated, for example a special control bit can be set, in the other case it can be deleted.

This can be done using the following query steps, for example:

If (COUNTER1> COUNTERL _lim ) there is a diagonal entanglement

On the other hand (if COUNTER1 <COUNTER _{in the} ι)

There is no diagonal entanglement

Since the COUNTER1 can count up to ZÄHLERl _max and the situation above the value ZÄHLERl _{liml is} considered to be recognized, the mechanism has a "memory" of ZAHLERl _max minus ZÄHLERlι _in ι times the cycle time. A further run-on effect will usually occur because the Control phases on the diagonal are maintained longer than the situation of the diagonal axis entanglement.

To avoid this, a second counter (COUNTER2) is set to a start value COUNTER2 _start when a diagonal entanglement is detected (step 27). If diagonal entanglement is not recognized (step 28) or outside of an active ASR control, this counter is set in a NEN time grid decremented to the value 0 (step 29). This period of time is, for example, 10 seconds. If the ASR control becomes active again due to overturning drive wheels within this "run-on time" and the above-mentioned conditions continue to exist (step 30), then when the COUNTER1 is one in comparison to the value COUNTER _1m ι the control _bit has already been set (step 32), the control _bit has already been set (step 32), otherwise a return to the ASR main program (step

33). The detection time is reduced significantly in this situation. The disadvantage mentioned above is thus reliably avoided.

With the help of the following query, these conditions (counter2) can be recognized, for example:

If ((COUNTER2> 0) and (slip conditions of a diagonal entanglement detected) and (ASR active) Then if (COUNTER1> = COUNTER1 _ιm2 )

Diagonal entanglement detected

According to the invention, all of the steps described above can advantageously be implemented by a program-controlled circuit as corresponding program steps or by a subroutine within an ASR system.

However, the steps can also be implemented with the aid of a circuit arrangement. FIG. 3 shows the block diagram of a circuit arrangement which shows, by way of example, the essential electrical / electronic components of an embodiment for detecting a diagonal axis interlock according to the invention. The first determination circuit 40 is essential to the invention. The first determination circuit 40 has a first, second, third and fourth evaluation circuit 41, 42, 43, 44 for evaluating a slip of the wheels on the secondary axle (circuit 41), the wheels of the respective two diagonally opposite wheel pairs (circuit 42 and 43), and the wheels on the primary axis (circuit 44). Inputs 45, 46, 47, 48 of the evaluation circuits 41, 42, 43, 44 are connected to corresponding outputs 49, 50, 51, 52 of a detection circuit 54 for detecting the measured turning behavior or changes in turning behavior or drive slip of the individual driven wheels. The first determination circuit 40 also has an integrator 55 and a signal generator 56. If, based on the evaluation by the first, second, third and fourth evaluation circuit, inputs 45, 46, 47, 48 of the evaluation circuits 41, 42, 43, 44 identify typical slip conditions for a diagonal axis interlocking over a predetermined period of time with the aid of the integrator 55 a signal is generated with the aid of the signal generator 56 and fed to an input 58 of a control circuit 59 via an output 57 of the signal generator 56 in order to trigger a corresponding ASR control intervention. In a preferred embodiment, it is provided that the first determination circuit 40 is assigned a second determination circuit 60 for determining a vehicle reference speed on the basis of measured values, and that the first determination circuit 40 has a comparator 61, which comparator 61 has an input 62 for one out of one Output 63 of the second determination circuit 60 has an incoming signal for the determined vehicle reference speed. With the aid of the comparator 61, the determined vehicle reference speed is compared with a predetermined limit value. The comparator is connected here via an output 64 to an input 65 of the evaluation circuit 41 and does not generate directly or via here shown further circuits a signal so that the evaluation by the evaluation circuits 41, 42, 43, 44 only takes place if the vehicle reference speed is lower than the predetermined limit value. In this case, the first determination circuit will only generate a signal for the presence of a diagonal axis interlock if the determined vehicle reference speed falls below the predetermined value, which means in particular in the case of a driving situation in “difficult” terrain at low vehicle speeds.

Claims

Patent claims 1. Method for vehicle control, in particular for traction control (ASR), characterized in that a diagonal axle articulation is determined and is evaluated as a controlled variable. 2. The method according to claim 1, characterized in that after determining the diagonal axle articulation using vehicle control means, the effect of a partial or complete locking of a center, front axle and / or rear axle differential is achieved and / or that a center, front axle and/or rear axle differential is partially or completely locked using a differential lock that may be present. 3. The method according to claim 1 or 2, characterized in that after determining the diagonal axle articulation, an average brake pressure level corresponding to the required traction on the wheel brakes of the controlled wheels is set at a minimum drive slip and maintained for a certain period of time. 4. The method according to one of claims 1 to 3, characterized in that after determining the diagonal axle articulation, the control threshold of the traction control system is additionally lowered. 5. Method according to one of claims 1 to 4, characterized in that the determined diagonal axle articulation is evaluated as a controlled variable and/or a corresponding control function of the vehicle control system is only activated when the vehicle speed, in particular a calculated or estimated vehicle reference speed, exceeds a predetermined vehicle speed limit value, preferably in the range from 3 to 15 km/h. 6. Method for detecting a diagonal axle articulation of a vehicle with all-wheel drive and a vehicle control system, in particular traction control (ASR), characterized in that the diagonal axle articulation is determined on the basis of the wheel slip, the rotational behavior and / or changes in the rotational behavior of the individual driven wheels. 7. A method for detecting a diagonal axle articulation according to claim 6, characterized in that the rotational behavior of the individual driven wheels is measured and evaluated to determine the traction slip and other controlled variables and that a diagonal axle articulation is based on a drive slip of the individual ones that is above a predetermined limit value Wheels are determined. 8. The method according to ^claim 6 or 7, characterized in that a diagonal axle articulation is determined on the basis of the rotational behavior and / or changes in the rotational behavior of at least two transversely opposite wheels and of two diagonally opposite pairs of wheels. 9. The method according to claim 7 or 8, characterized in that a diagonal axle articulation is determined when certain traction slip conditions are met for a predetermined period of time. 10. The method according to claim 9, characterized in that a diagonal axle articulation is detected when the following conditions are met for a predetermined period of time, that a) on the secondary axle only one wheel has a drive slip that exceeds a predetermined limit value, b ) there is drive slip above the predetermined limit value on both of two diagonally opposite wheels of a pair of wheels and c) there is drive slip below the predetermined limit value on a first wheel of the primary axle, which first wheel has a second wheel on the primary axle a drive slip that is above the predetermined limit value or at least a lower brake pressure, compared to the second wheel of the primary axle with a drive slip that is above the predetermined limit value, is present in the wheel brake of the first wheel of the primary axle, which first wheel corresponds to the second wheel of the primary axis with a drive slip that is above the specified limit. 11. The method according to claim 10, characterized in that the state of a diagonal axle articulation is determined when conditions a) to c) are met for a period of 0.3 to 1.5 seconds. 2. The method according to one of claims 9 to 11, characterized in that a diagonal axle articulation is determined when the specific traction slip conditions are met for a relatively short period of time, preferably 50 to 200 msec, and if the last diagonal axle articulation determined beforehand is at most a few Seconds, preferably 5 to 15 seconds ago. 13. The method according to one of claims 8 to 12, characterized in that a traction slip, based on the wheel rotational speed of the spinning wheel, in the order of magnitude between 10 km/h to 40 km/h, is specified as a traction slip limit value . 14. The method according to one of claims 8 to 13, characterized in that the traction slip limit value on a wheel is considered to be exceeded when a control process of the traction control system on the respective wheel begins or stops. 15. Method for vehicle control, in particular for traction control (ASR), characterized in that the diagonal axle articulation is determined using a method according to one of claims 6 to 14. 16. Circuit arrangement for detecting a diagonal axle articulation of a vehicle with all-wheel drive and a traction control system, which vehicle has a detection circuit for detecting measured changes in rotational behavior of the driven wheels, characterized in that that the circuit arrangement has a first determination circuit (40) for determining a diagonal axle articulation of the vehicle based on the changes in the rotational behavior of the driven wheels detected by the detection circuit (54). 17. Circuit arrangement according to claim 16, characterized in that the first determination circuit (40) has a first evaluation circuit (41) for evaluating a Slip of the wheels on the secondary axle has that the first determination circuit (40) has a second and a third evaluation circuit (42, 43) for evaluating a slip of the wheels of the two diagonally opposite pairs of wheels, that the first determination circuit (40) has a fourth evaluation circuit (44) for evaluating slip of the wheels on the primary axle, and that the first determination circuit (40) has an integrator (55) and a signal generator (56) for generating a signal when using the Evaluation by the first, second, third and fourth evaluation circuits (41, 42, 43, 44) over a predetermined period of time, certain slip conditions typical for a diagonal axle interlocking are recognized. 18. Circuit arrangement according to claim 16 or 17, characterized in that the first determination circuit (40) is assigned a second determination circuit (60) for determining a vehicle reference speed based on measured values, and that the first determination circuit (40) has a comparator (61) to compare the determined vehicle reference speed with a predetermined limit value and wherein the first determination circuit (40) sends a signal for the presence a diagonal axle articulation is only generated if the determined vehicle reference speed falls below the predetermined value.